Textured proteic fiber matrix with included solid, liquid or gaseous particles

ABSTRACT

A food product comprising a matrix of fibers such as proteinaceous fibers, the matrix having inclusion bodies dispersed therein. The inclusion bodies may be solid, liquid or gases which can be intercalated within or between the fibers so as to weaken and disrupt the integrity of the fibers and tenderize the food products.

The National stage application filed under 371 of PCT/GB96/01056 filedMay 2, 1996.

The present invention relates to food (e.g. protein) products, and inparticular to textured plant and/or animal protein products which have amouthfeel similar to that of meat.

BACKGROUND OF THE INVENTION

The demand for alternative non-meat protein sources in the 1950s led tothe development of a number of processes for texturing plant proteins ormixtures of plant and animal proteins to form meat-like materials.

These processes are very diverse, but in many cases three common stepsare involved, vizg (1) an initial hydration and mixing step to form aslurry or dough, followed by (2) a shearing (and in some cases heating)step to denature proteins and produce aligned protein fibres (a reducingagent is often present at this stage to promote denaturation by ruptureof disulphide bonds), and finally (3) a setting step to fix the fibrousstructure, setting often being achieved by rapid temperature and/orpressure change, rapid dehydration or chemical fixation. Therestructured material is usually extruded through a die orifice to shapethe product prior to setting. One of the most common methods ofproducing textured proteins is by extrusion cooking (see Gutcho, M.(1973), "Textured foods and allied products", Food Technology Review No.1, Noyes Data Corporations Park Ridge, N.J., USA, and Harperg J. M.(1981), Chapter 13 "Textured Plant Proteins", in Extrusion of Foods Vol.II, CRC Press Inc., Boca Raton, Fla., the contents of which areincorporated herein by reference).

In this process a protein-rich flour (typically 50-80% protein) is fedinto a closed barrel containing one or two screw shafts. The screwsconvey the material forwards where it is mixed with water and kneaded toform a dough. The dough is then conveyed forward into a zone containingscrew elements designed to impart shear, this area also being hot(100-170 degrees centigrade) and under pressure (100-1000 psi). Theseextreme conditions cause the material to melt and adopt a fibrouscharacter. The fibres become aligned in the direction of shear appliedby the screw elements.

The melt is then forced through a single, or a number, of die orifices.As the material extrudes through the die, super-heated water present inthe melt flashes off as steam, causing a simultaneous expansion("puffing") of the material. At this point the material sets, and theprocess therefore produces a continuous stream of textured product. Thisprocess is shown schematically in FIG. 7.

Although fairly dry at this stages the product is usually dried furtherto increase shelf-life. Before use the product is fully rehydrated (thewater absorption of such products is usually in the region of threetimes their own weight).

Natural fibrous protein sources, such as meat and mycoprotein (soldunder the Trade Mark Quorn), have textures which elicit distinctivesensations during chewing and breakdown in the mouth. This mouthfeel isan extremely important acceptability/quality parameter of meat andmeat-substitutes, and there is a window of texture associated byconsumers with various protein-based products. For example, the rate atwhich the product breaks down on chewing, the number of chews requiredbefore the material can be swallowed, the textures exposed to the teethand tongue during chewing are all important in determining theacceptability of the product, especially in the case where the productis a meat substitute.

Extrusion of conventional textured protein products, such as those madewith soya or wheat proteins tend to result in very fibrous material witha meat-like appearance. However, when hydrated, the system of fibresform a resilient and continuous matrix. The result is a very elastic andtough product which exhibits a poor mouthfeel. Many products haverubbery, tough, slimy and spongy mouthfeels.

One solution to this problem is to use the textured protein products asmeat substitutes or analogues in comminuted form. However, this limitstheir application to products where minced meat would conventionally beused, for example in burgers, sausages and similar products.

Another solution has been to dilute the protein with starchy materials,such as wheat flour or corn starch. However, although this approach hasbeen found to soften the products it does not impart a meat-likemouthfeel--the product is often still too chewy and sliminess may beincreased.

It is an object of the present invention to provide food products (forexample, textured food products) having an improved mouthfeel.

SUMMARY OF THE INVENTION

According to the present invention there is provided a food productcomprising a matrix of fibres having inclusion bodies dispersed therein,the inclusion bodies being intercalated within or between the fibres toweaken or disrupt them and so tenderize the product.

Preferably, the product is an extrudate, the fibre matrix being producedby extrusion.

The fibres may comprise proteinaceous fibres, which may have a proteincontent greater than 50% (e.g. greater than 80%). They are typically(but not necessarily) those producible by shear-alignment of fibrils(e.g. protein fibrils) during extrusion of slurries or doughs (e.g.through a die orifice of a (twin) screw extruder). They may compriselong bundles of extended peptide chains, linked for example bydisulphide bonds.

The product of the invention is preferably a textured protein product.

The textured protein product may be based on any protein or mixture ofproteins, including animal proteins (for example low grade meat and/oroffals). Preferably, the protein is plant protein (for example plant(e.g. seed) storage proteins), vegetable, leguminous (e.g. soya, pea,ground nut or lupin), cereal (e.g. wheat or maize) or tuberous (e.g.potato), animal, fish or fungal protein, or derivatives/combinationsthereof.

The inclusion bodies may be intercalated between and/or within thefibres or fibrils (or bundles thereof). Their precise distribution isnot critical to the invention, so long as they serve to weaken ordisrupt the proteinaceous fibre matrix (and so tenderize the product).

The inclusion bodies may for example effectively interrupt (or break)the proteinaceous fibres (and/or their inter-/intraconnections) at oneor more points along their length, or locally weaken them so that theyare prone to breakage at these points.

The action of the inclusion bodies on the fibres may be mediated bypurely physical effects (e.g. physical dissociation or perturbation offibre structure and/or increase in the gross density of the product), bychemical effects (local changes in the chemical constitution of thefibres in the microenvironment surrounding the inclusion body) or by acombination of both.

Without wishing to be bound by any theory, it is thought that themechanism of action of inclusion bodies comprised of oils and/or fatsinvolves the formation of lipid interfaces within the hydrated proteinmatrix, which interfaces act as hydrophobic barriers that prevent theformation of a continuous protein network.

The inclusion bodies are produced by adding one or more texturemodifying additives to the protein(s) to be textured. The texturemodifying additive used during manufacture may be the inclusion bodiesin the form in which they are present in the final product (being e.g.in the form of a particulate solid). Alternatively, the additive may bea composition (e.g. a salt solution) which gives rise to inclusionbodies during a subsequent processing step (e.g. during the conditionsimposed by extrusion through a die orifice of a twin screw extruder).

Sufficient texture modifying additive is used to give rise to inclusionbodies in the final product at a concentration sufficient to tenderize(and/or soften) the products and preferably at a concentrationsufficient to produce a meat-like mouthfeel. In preferred embodiments,the textured protein products of the invention have a clean bite without(or with reduced) rubberiness, sponginess or sliminess.

The optimum concentration of texture modifying additive is readilydeterminable by titrating the amount of texture-modifying additiveagainst mouthfeel or strength of the end products and depends on thenature of the protein(s) to be textured and the desired mouthfeel Ingeneral, for a meat-like mouthfeel lower concentrations are required forpea-based protein products than for gluten-based products

The inclusion bodies may comprise solids liquid or gaseous bodies, or acombination thereof. Preferably, the inclusion bodies comprisemechanically robust particles. The inclusion bodies may comprise oil orfat particles, and particularly preferred is vegetable oil or fat,especially that used in the form of full fat soya flour (e.g. that soldas Trusoy™).

The inclusion bodies may also comprise particles of an inorganic salt.Calcium or magnesium salts are preferred.

The inclusion bodies may comprise an insoluble material, for example aninsoluble organic or inorganic salt. Additionally (or alternatively),the inclusion bodies may comprise a soluble or insoluble polymer, forexample cellulose particles or fibres.

In a preferred embodiments the inclusion bodies comprise particles ofcalcium sulphate dihydrate (gypsum). Calcium sulphate dihydrate is aningredient with unrestricted usage, and this embodiment is particularlyadvantageous for use with human foodstuffs.

In another preferred embodiments the inclusion bodies comprise particlesof dicalcium phosphate. This substance is commonly added at lowconcentrations during protein processing for various reasons (e.g.nutritional), but is not used to produce tenderizing inclusion bodies.

The inclusion bodies may advantageously comprise mixtures of: (a) gypsumand cellulose, (b) gypsum, cellulose and fat or oil, (c) gypsum and fator oil, (d) dicalcium phosphate and cellulose, (e) dicalcium phosphateand fat or oil, (f) dicalcium phosphate, cellulose and fat or oil, (g)gypsum and dicalcium phosphate, (h) gypsum, dicalcium phosphate andcellulose and/or fat or oil.

The fat or oil may be pure or in the form of full fat soya flour, and/orincorporated in fat powders or fat-filled powders.

The diameter of the inclusion bodies is preferably similar to that ofthe proteinaceous fibres. In many embodiments, the inclusion bodies arebetween 1 and 100 um in diameters for example between 10 and 100 um.

In another aspect the invention relates to a method for producing a foodproduct comprising the steps of: (a) forming a matrix of fibres (e.g.proteinaceous fibres); and (b) introducing discontinuities into thematrix by intercalating discrete inclusion bodies within or between thefibres to weaken or disrupt them.

The inclusion bodies are preferably derived from a texture modifyingagent present during the matrix forming step. The matrix may be formedfrom a proteinaceous slurry, powder or dough, and is conveniently formedby extrusion.

In embodiments in which extrusion is used to create a fibre matrix, theextrusion may be high moisture extrusion, for example at a moisturecontent of greater than 40%.

Particularly preferred is high moisture extrusion at a moisture contentof 40-80% (e.g. 50-70%).

The extrudate may be cooled by means of a cooled die. The cooled die mayadvantageously comprise a long cooled die, for example greater than 0.3m in length. Particularly preferred are dies of 0.3-5.0 m (e.g. 2.0-4.0m) in length.

The extrudate is preferably pumped from the extruder, for example into adie (such as the cooled dies as described above). In these embodiments,the pump (which may for example be a gear pump) may be located betweenthe extruder and die (for example as described in EP0398315).

The invention also relates to a foodstuff (e.g. foodstuff) comprisingthe product of any one of the preceding embodiments. The foodstuff mayadvantageously be a meat substitute or meat analogue, and may be in theform of discrete chunks.

The invention also contemplates a method for producing a texturedprotein product comprising the steps of: (a) forming a matrix ofproteinaceous fibres in the presence of a texture modifying agent, and(b) processing the matrix under conditions whereby the texture modifyingagent forms discrete inclusion bodies intercalated within or between thefibres to weaken or disrupt them.

The matrix is preferably formed from a proteinaceous slurry or dough,and in step (b) the processing step may comprise extruding the matrixthrough a die orifice of an extruder, e.g. in a process according tothat shown in FIG. 7.

The invention will now be described in greater detail by way of example.The examples are for illustrative purposes only and are not intended tobe limiting in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a light micrograph (×425) showing a longitudinal section ofextruded wheat gluten with 0.7% cysteine. Aqueous Light Green was usedto stain plant protein. This was followed by counterstaining with Lugolsiodine solution for plant carbohydrate. This figure shows the dense,continuous protein structure produced by extrusion of wheat gluten with0.7% cysteine (used as a process aid). The dark particles present havestained black with iodine hence are likely to represent residualnon-starch polysaccharide in the gluten.

FIG. 2 is a light micrograph (×425) showing a longitudinal section ofextruded gluten containing 0.7% cysteine and 10% calcium sulphate.Staining is as described for FIG. 1. This figure demonstrates the effectof including calcium sulphate in extruded gluten. The structure becomesdisrupted (compared to FIG. 1) and unstained particles, thought to becalcium sulphate can be seen interspersed between the proteinaceousfibres.

FIG. 3 is a light micrograph (×425) showing a longitudinal section ofextruded gluten containing 0.7% cysteine and 1% vegetable oil. Stainingis as described above for FIG. 1. This figure demonstrates thedisruptive influence of adding fat to the structure of extruded gluten.This can be compared with FIG. 1 which relates to a sample without addedfat.

FIG. 4 is a scanning electron micrograph (SEM) of a longitudinal sectionof extruded gluten containing 0.7% cysteine. This micrograph shows therelatively smooth fibrous surface.

FIG. 5 is an SEM of a longitudinal section of extruded gluten containing5% calcium sulphate and 7.5% cellulose (as shown in FIG. 6). Thismicrograph shows the smooth surface of the protein matrix disrupted byintact particles of cellulose fibre and calcium sulphate.

FIG. 6 is an SEM of a section of extruded gluten containing 0.7%cysteine, 5% calcium sulphate and 7.5% cellulose fibre. The white areas(three examples of which are circled) have been positively identified ascalcium sulphate using x-ray elemental mapping. This figure shows thedispersion of particulate material in the protein matrix. Reference tothe 100 μm scale bar reveals that particles tend to be in the range 1-75μm.

FIG. 7 shows in schematic form a typical extrusion process for theproduction of textured protein products.

FIGS. 8 and 9 show contour diagrams depicting an assessment of eatingquality by a panel of experts using a scale from 1.0 (very poor) to 5.0(excellent).

DESCRIPTION OF PREFERRED EMBODIMENTS

Unless otherwise stated, all percentages are expressed on a dry weightbasis.

Example 1

A dry powder mix of gluten, 0.2% sulphur (as a reducing agent) andvarious amounts of texture modifying additive (dicalcium phosphateand/or Trusoy™) was fed into the feed spout of a Wenger TX52 twin screwextruder (fitted with a single 7 mm circular die orifice) at a rate of60 kg dry mix per hour. The extruder was also fed with water at a rateof 12 kg per hour. The residence time was about 30 sec, the temperaturebetween 50-160 degrees centigrade and the pressure between atmosphericand 1000 psi (temperature and pressure increasing to peak at the die).

The results are shown in FIG. 8, which shows a contour diagram depictingan assessment of eating quality by a panel of experts using a scale from1.10 (very poor) to 5.0 (excellent).

The presence of between 8 and 30% of dicalcium phosphate had abeneficial effect on eating quality. The benefit was particularly markedwhen the dicalcium phosphate was used at fifteen to twenty-five percentalong with Trusoy™ at between 0.5 and 4%.

Example 2

A mixture based on wheat gluten dough was prepared as described above,but pure fat or oil replaced the full fat soya flour (Trusoy™) in thetexture modifying additive.

Similar results to those shown in FIG. 8 were obtained, indicating thata major functional component of full fat soya flour is the fat (full fatsoya flour comprises about 20% fat).

Example 3

A mixture based on wheat gluten dough was prepared as described inExample 1, but calcium sulphate dihydrate (gypsum) was used in place ofthe dicalcium phosphate at up to 20%.

Similar results to those shown in FIG. 8 were obtained.

Example 4

A mixture based on wheat gluten was prepared as described for Example 3,but cellulose fibre was also added. It was found that cellulose fibrecould at least partly replace the calcium salt. The results of the useof various concentrations of calcium sulphate dihydrate and cellulosefibre (along with 2% soya oil) are shown in FIG. 9, which shows acontour diagram depicting an assessment of eating quality by a panel ofexperts using a scale from 10 (very poor) to 500 (excellent).

Improvement in eating quality were greatest when the levels of cellulosefibre and calcium sulphate were each greater than about 7.5%.

Example 5

A wheat gluten dough was prepared using conventional procedures. Variousamounts of texture modifying additive in the form of gypsum and/orvegetable fat (hardened palm oil) were mixed with the dough, and themixture then extruded using conventional techniques.

The extruded products were rehydrated and subjected to textural analysisusing an instron universal texture analyser. The test involvespenetrating a set weight of hydrated material with a multi-toothedprobe. The energy required to reach the point at which the test materialrutures was recorded as a measure of toughness.

The results are shown in Table 1. The show that significantly lessenergy is required to penetrate material containing gypsum alone, fatalone, or both fat and gypsum compared with a product with no texturemodifying additives.

Shown in Table 1, sample 2 containing 5% gypsum requires 22% less energyto break compared to sample 1 (no texture modifying additive). Theaddition of 1% vegetable table fat (sample 5) reduces the energy tobreak-point by 34% compared to the no additive control (sample 1).Gypsum and fat have an additive effect when the gypsum is present at 10%or more (samples 7 and 8).

                  TABLE 1    ______________________________________    The Effect of the Addition of Gypsum and/or Vegetable Fat on the    Mechanical Strength of Extruded Textured Gluten                          Energy to          Veg Fat Gypsum  Break Point    Percent Change in    Sample          (%)     (%)     (mJ)    S.D. n = 9                                         E. to B.P    ______________________________________    1     0       0       8381    750    --    2     0       5       6537    759    -22    3     0       10      5901    561    -30    4     0       15      5446    442    -35    5     1       0       5560    311    -34    6     1       5       5425    167    -35    7     1       10      4690    375    -44    8     1       15      4448    348    -47    ______________________________________

Example 6

A textured gluten chunk product having the composition shown in Table 2(hereinafter referred to as the Standard formulation) was prepared asdescribed below.

                  TABLE 2    ______________________________________           Ingredients                     %    ______________________________________           Wheat fibre                     5.0           Vitacel fh wf600           Satro     1.5           Hydrogenated           Vegetable fat           FP75           Gypsum    5.0           Vital Wheat                     70.3           Gluten           Cysteine  0.7           Hydrochloride           Wheat Flour                     15.0           Glycerol  1.0           Monostearate           Flavour   3.0    ______________________________________

The ingredients were made up and mixed for 7 minutes using a GardinerRibbon Mixer. The insoluble salts, fat and fibres were added at themixing stage. The mixes were then fed into the K-tron volumetric WengerTX52 extruder feeder which delivered the mix at a constant throughput(98 kg/hr), to the extruder barrel via the preconditioner. The barrelcontained twin screws with a standard configuration. The screws conveyedthe material forward where it mixed with water (pumped in at 17%). Thematerial formed a dough which then passed through screw configurationsthat produced high shear. The pressure and temperature in this regionwas high (100°-170° C.) which caused the material to melt. The melt wasthen forced through a single loam square die. The expanded product wasthen dried at 80° C. for one hour in the APV drier in order to extendthe shelf-life. The material was then ready for analysis.

The Instron Universal Texture Analyser was used to measure thetenderness of the product. The test used involves penetrating a setweight of hydrated material with a multi-toothed probe (the Kramer Cell)and recording the energy required to rupture the material. The Kramercell was fitted to the crosshead of the Instron. The cell consisted ofmulti-toothed probes which cut the gluten chunks until they fell throughthe grid of the bottom piece. The Bioyield (N) is the maximum forceattained during crushing of the material, and was found to be a goodindicator of the textural differences between the varying test samples.

The samples for instron testing were prepared as follows:

(1) Place sample into foil container;

(2) Pour over 200 g of cold tap water;

(3) Cover sample with lid and seal;

(4) Place in a preheated oven at 180° C. for 20 minutes;

(5) Remove from oven and allow samples to equilibriate to roomtemperature (20°-25° C.);

(6) Note temperature of the chunks prior to testing.

The Bioyield values for products having the composition shown in Table 2are shown in Tables 4, 6 and 8 (rows designated "Standard").

Example 7

A range of different compositions were prepared as described in Example6, except that the Satro Fat FP75 was replaced with one of a number ofdifferent fats/oils listed in Table 3.

                  TABLE 3    ______________________________________    Ingredient     Source    ______________________________________    Satro Fat FP75 Satro    Rapeseed Oil   Bcoco Ltd. Liverpool    Cod Liver Oil  Seven Seas Ltd. Hull    Chicken Fat    Lucas Ingredients. Kingswood    Coconut Oil    Anglia Oils Ltd. Humberside    Groundnut Oil  Anglia Oils Ltd. Humberside    Beef Suet      Spillers Technical Advancement Centre.                   Cambridge    High Oleic Sunflower Oil                   Lucas Ingredients. Kingswood    ______________________________________

The fats/oils were first melted down in a water bath set at 80 degreescentigrade and then added to 1.5% wt. with a peristaltic pump duringextrusion. The results are shown in Table 4.

                  TABLE 4    ______________________________________                    Bioyield                    (N)    Sample          Mean     sd    ______________________________________    Control         637.9    43.2    Standard        512.5    15.8    Rapeseed        492.3    24.4    Fish            467.3    37    Chicken         492.6    29.1    Coconut         499.8    20.7    Groundnut       533.1    41.6    Beef            506.3    33.3    Sunflower       512      39    ______________________________________

The results indicate that all of the fats/oils tested reduce theBioyield of the extruded product. As bioyield measures the maximumattained during the crushing of the material, the lower the force, theless effort is required to chew the samples and therefore the moretender the product.

The control (containing no fats/oils), had the highest bioyield values,while the lowest bioyield value was evident in the sample containingfish oil (467.3N),

Generally there was not a great deal of variation in bioyield values forall the fat and oil samples. The groundnut oil seemed to have the leastbeneficial effect on the texture. No obvious trend was found betweenvegetable fats/oils and animal fats/oils.

The fat and oil samples were found to be significantly different to thecontrol which contained no fats or oils. Fish oil showed the largestsignificant differences to the control. None of the fats or oils weresignificantly different to the standard (Satro fat FP75).

Example 8

A range of different compositions were prepared as described in Example6, except that the Vitacel fibre WF600 was replaced with one of a numberof different fibres as listed in Table 5.

                  TABLE 5    ______________________________________    Ingredient       Source    ______________________________________    Vitacel fibre WF600                     Allehem International. Berkshire    Wheat fibre Isolate ID 95                     ID Food Concepts. France    Oat fibre ID 82  ID Food Concepts. France    Barley fibre 1   ID Food Concepts. France    Pea fibre EXAFINE                     Cosnera. Netherlands    Potex Potato fibre PP                     Avebe    ______________________________________

The fibres were all added to 5.0% wt (the potato and pea fibre weremilled down using a cyclone mill to approximately <200 microns). Theresults are shown in Table 6.

                  TABLE 6    ______________________________________                    Bioyield                    (N)    Sample          Mean     sd    ______________________________________    Control         572.3    42.2    Standard        512.5    15.8    Wheat           540.1    25.4    Oat             540.6    41.1    Barley          498.8    26    Pea             495.9    40.3    Potato          447.6    35.7    ______________________________________

The control (with no added fibres) showed the highest bioyield value.There was no significant variation in bioyield values between thevarious fibres. Potato fibre produced a relatively low bioyield valuewhich suggests that it has the most tenderising effect on the product.The standard formulation containing Vitacel showed no significantbeneficial effect on the texture as compared to the other fibres added.

All the fibres showed a significant difference when compared to thecontrol, except for the sample containing Oat fibre which showed nosignificant difference at a 5% level in this substituted standardformulation. All fibre types (except for Oat) showed no significantdifference when compared to the standard (Vitacel WF600).

Example 9

A range of different compositions were prepared as described in Example6, except that the gypsum was replaced with one of a number of differentinsoluble salts as listed in Table 7.

                  TABLE 7    ______________________________________    Ingredients      Source    ______________________________________    Gypsum           Annetstar. Grimsby    Magnesium Sulphate                     Sigma Chemical. UK    M7506    Dicalcium Phosphate                     Spillers Petfoods. Cambridge    Calcium Carbonate                     Spillers Petfoods. Cambridge    Iron Oxide    ______________________________________

The salts were all added to 5.0% wt. The results are shown in Table 8.

                  TABLE 8    ______________________________________                    Bioyield                    (N)    Sample          Mean     sd    ______________________________________    Control         700.6    23.9    Standard        512.5    15.8    MgSO.sub.4      650.5    29.3    DCP             663.6    67    CaCO.sub.3      546.8    39.5    Iron Oxide      573.8    34.4    ______________________________________

Gypsum (present in the standard formulation), produced a remarkably lowbioyield value compared to the other insoluble salts added. Theinsoluble salts showed varying degrees of significance when compared tothe standard and the control. The standard (gypsum), magnesium sulphate,iron oxide and calcium carbonate showed a significant difference whencompared to the control. Calcium carbonate showed no significantdifference when compared to gypsum in the standard formulation. Thusgypsum, magnesium sulphate, iron oxide and calcium carbonatesignificantly improved the texture of the gluten chunk. Calciumcarbonate can replace Gypsum in the standard formulation.

The invention is of general application to all fibrous food products,and is not limited to textured protein products comprising proteinaceousfibres. It may be applied, for example, to fibrous carbohydrateproducts.

We claim:
 1. A food product comprising a matrix of proteinaceous fibreshaving a plurality of inclusion bodies dispersed therein, said inclusionbodies being intercalated within or between the fibres so as to weakenand disrupt the integrity of said fibers and tenderize the food product,said inclusion bodies comprising solid particles of an insoluble organicor inorganic salt.
 2. The food product of claim 1 wherein the fibres areproteinaceous fibres having a protein content of greater than 50%. 3.The food product of claim 2 wherein the proteinaceous fibres have aprotein content of greater than 80%.
 4. The food product of claim 2wherein the proteinaceous fibres are selected from the group consistingof animal protein, plant protein, vegetable protein, leguminous protein,cereal protein, tuberous protein, fish protein, fungal protein, andderivatives and mixtures thereof.
 5. The food product of claim 1 whereinthe inclusion bodies are mechanically robust particles.
 6. The foodproduct of claim 1 wherein the inclusion bodies also include at leastone of oils, fats, soluble and insoluble polymers, and mixtures thereof.7. The food product of claim 6, wherein the inclusion bodies include atleast one of full fat soya flour, fat powder, fat-filled powder, animaloil and fat, vegetable oil and fat, and mixtures thereof.
 8. The foodproduct of claim 7 wherein the inclusion bodies also include at leastone of Satro Fat FP75, rapeseed oil, cod liver oil, chicken fat, coconutoil, groundnut oil, beef suet, high oleic sunflower oil, full fat soyaflour, and mixtures thereof.
 9. The food product of claim 6 wherein theinclusion bodies are selected from the group consisting of an inorganicsalt of calcium, iron and magnesium, and mixtures thereof.
 10. The foodproduct of claim 9 wherein the inclusion bodies include at least one ofcalcium sulphate dihydrate, magnesium sulphate, dicalcium phosphate,calcium carbonate, iron oxide, and mixtures thereof.
 11. The foodproduct of claim 6 wherein the inclusion bodies also include at leastone of a soluble or insoluble polymer of gluten, cellulose,hemicellulose, pectin, xylan, glucan, lignin, chitin, and mixturesthereof.
 12. The food product of claim 11 wherein the inclusion bodiesalso include a derivative of at least one wheat, oat, barley, pea,potato and mixtures thereof.
 13. The food product of claim 6 wherein theinclusion bodies are selected from the group consisting of (a) gypsumand a soluble or insoluble polymer; (b) gypsum, a soluble or insolublepolymer, and fat or oil; (c) gypsum and fat or oil; (d) dicalciumphosphate and a soluble or insoluble polymer; (e) dicalcium phosphateand far or oil; (f) dicalcium phosphate, a soluble or insoluble polymer,and fat or oil; (g) gypsum and dicalcium phosphate; and (h) gypsum,dicalcium phosphate, a soluble or insoluble polymer, and fat or oil. 14.The food product of claim 13 wherein the matrix of fibers comprisesgluten, the soluble or insoluble polymer comprises wheat and the fat oroil comprises vegetable fat.
 15. The food product of claim 13 whereinthe inclusion bodies comprise a mixture of a soluble or insolublepolymer, fat and gypsum.
 16. The food product of claim 15 wherein thesoluble or insoluble polymer is present at greater than 2%, the fat ispresent at greater than 0.1% and the gypsum is present at greater than2%, on a dry weight basis of the product.
 17. The food product of claim16 wherein the soluble or insoluble polymer is present at 5%, the fat ispresent at 1.5% and the gypsum is present at 5%, on a dry weight basisof the product.
 18. The food product of claim 1 wherein the meandiameter of the fibres is substantially the same as that of theinclusion bodies.
 19. The food product of claim 1 wherein the meandiameter of the inclusion bodies is less than 500 μm.
 20. The foodproduct of claim 19 wherein the mean diameter of the inclusion bodies isbetween 10 and 100 μm.
 21. The food product of claim 11, wherein thefood product is a pet food.
 22. The food product of claim 21, whereinthe pet food is a meat substitute in the form of discrete chunks.
 23. Amethod for producing a food product comprising forming a matrix of foodproteinaceous fibres and introducing a plurality of inclusion bodiesinto the matrix, within or between the fibres, so as to weaken anddisrupt the integrity of said fibres and tenderize the food product,said inclusion bodies comprising solid particles of insoluble organic orinorganic salt.
 24. The method of claim 23 wherein the inclusion bodiesare derived from a texture modifying agent that is present during thestep of forming a matrix of food fibres.
 25. The method of claim 23wherein the matrix of food fibres is formed by extrusion.
 26. The methodof claim 25 wherein the extrusion is high moisture extrusion with amoisture content of greater than about 40%.
 27. The method of claim 26wherein the moisture content is between 40 and 80%.
 28. The method ofclaim 25, wherein the extruded matrix of fibres is cooled by means of acooled die.
 29. The method of claim 28, wherein the cooled die isgreater than 0.3 m in length.
 30. The method of claim 29 wherein the dieis between 2.0 and 4.0 m in length.
 31. A method of producing a foodproduct comprising:(a) forming a matrix of proteinaceous food fibres byhigh moisture extrusion with a moisture content of greater than 40%; and(b) introducing a plurality of inclusion bodies into the matrix, withinor between the fibres, so as to weaken and disrupt the integrity of thefibres and tenderize the food product, said inclusion bodies comprisingsolid particles or organic or inorganic salt.